This study was aimed to investigate the attitude of principals, supervisors and mentees towards action research as reflective practices in Postgraduate Diploma in Secondary School Teaching (PGDT). The samples used for this study consisted of 82 mentees, 38 Principals and 26 Supervisors taken from three clustered centres by using stratified random sampling technique for mentees and principals whereas availability sampling techniques were employed for supervisors. To make the interpretation of data sound and to the point, the researcher used descriptive statistics (mean scores and standard deviations) to describe the nature of the data and the characteristics of the sample. Moreover, inferential statistics (one way ANOVA) was employed to compare a significant mean differences exist between and within groups of the most likely value of the variables. The findings from this study revealed a statistically significance mean difference among mentees for lack of innovative methodologies, lack of instructional materials and lack of dedication from lecturers and attitudes towards action research as reflective practices in the case of Haramaya clustered centre. Therefore, principals and supervisors of the implementing unit of the system should act morally, practically, professionally, ethically, responsibly and critically so as to accommodate professional need of the nation to bring behavioural changes and quality education for the Ethiopian children.